LED (Light Emitting Diode) has been applied to many fields due to its advantages of energy conservation, environmental protection, light weight, long service life, small volume, stable performance and the like. Especially in the field of illumination, LED has been more and more widely used, and is regarded as one of main light sources in illumination in future.
Generally, encapsulating a LED light-emitting device in the prior art comprises steps of: injecting polyphthalamide (PPA) or engineering plastic on a metal support or metal substrate, so as to form an optical cup; fixing one or a plurality of LED chips within the optical cup, and connecting the plurality of LED chips in serial/parallel through metal wires; and filling the optical cup with a gel mixed with a fluorescent powder. The luminous efficiency of the LED light-emitting device encapsulated in such manner is relatively low, because the metal support or metal substrate that is light-proof itself makes light emitted from the LED chips cannot transmit through the support or substrate and be output to the outside. Additionally, the light that is not output will generate a large amount of heat inside the optical cup, and no separated heat conduction path is provided for the LED chips, so that the heat generated by the LED chips will be excessively aggregated, resulting in that the reliability of the LED light-emitting device will be decreased in a manner of linear regularity. In fact, light output of the prior LED light-emitting device only accounts for 20% - 30% of its produced energy, and the other 70% - 80% of energy is not being utilized but generates heat. Therefore, how to improve the luminous efficiency of the LED light-emitting device, enhance its application function and prolong its service life become urgent issues to be solved.